Re: [PATCH v3 net 0/3] udp: Fix two integer overflows when sk->sk_rcvbuf is close to INT_MAX.

On Thu, 27 Mar 2025 13:26:52 -0700 Kuniyuki Iwashima wrote:

I got a report that UDP mem usage in /proc/net/sockstat did not
drop even after an application was terminated.

The issue could happen if sk->sk_rmem_alloc wraps around due
to a large sk->sk_rcvbuf, which was INT_MAX in our case.

The patch 2 fixes the issue, and the patch 1 fixes yet another
overflow I found while investigating the issue.

Test fails in the CI, unfortunately:

# 0.00 [+0.00] TAP version 13
# 0.00 [+0.00] 1..2
# 0.00 [+0.00] # Starting 2 tests from 2 test cases.
# 0.00 [+0.00] #  RUN           so_rcvbuf.udp_ipv4.rmem_max ...
# 0.00 [+0.00] # so_rcvbuf.c:150:rmem_max:Expected get_prot_pages(_metadata, variant) (49) == 0 (0)
# 0.01 [+0.00] # rmem_max: Test terminated by assertion
# 0.01 [+0.00] #          FAIL  so_rcvbuf.udp_ipv4.rmem_max
# 0.01 [+0.00] not ok 1 so_rcvbuf.udp_ipv4.rmem_max
# 0.01 [+0.00] #  RUN           so_rcvbuf.udp_ipv6.rmem_max ...
# 0.01 [+0.00] # so_rcvbuf.c:150:rmem_max:Expected get_prot_pages(_metadata, variant) (49) == 0 (0)
# 0.01 [+0.00] # rmem_max: Test terminated by assertion
# 0.01 [+0.00] #          FAIL  so_rcvbuf.udp_ipv6.rmem_max
# 0.01 [+0.00] not ok 2 so_rcvbuf.udp_ipv6.rmem_max
# 0.02 [+0.00] # FAILED: 0 / 2 tests passed.
# 0.02 [+0.00] # Totals: pass:0 fail:2 xfail:0 xpass:0 skip:0 error:0
not ok 1 selftests: net: so_rcvbuf # exit=1
-- 
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